Not least for hygienic reasons, blood remaining in the blood circuit after use of extracorporeal blood circuits is regularly removed therefrom.
One object of the present invention is to specify a further method for removing blood from an extracorporeal blood circuit or from a functional device at the end of a blood treatment session.
Further, a blood treatment apparatus by means of which the method according to the invention is feasible as well as control device provided for executing the method according to the invention, a suitable digital storage medium, a suitable computer program product and a suitable computer program are to be specified.
All advantages that are achievable by means of the method according to the invention may in certain embodiments according to the invention undiminishedly also be achieved by means of the apparatuses according to the invention.
The method according to the invention is suitable and intended for removing blood from an extracorporeal blood circuit which comprises at least one arterial line section and at least one venous line section, and/or for removing blood from a functional device which is or are connectable or connected with a blood treatment apparatus for the purpose of a blood treatment of a patient, or each from sections thereof.
The method according to the invention encompasses conveying the fluid present in the extracorporeal blood circuit after the end of the treatment by means of a blood pump which was already used for the blood treatment. While the blood pump conveyed fluid in a first conveying direction during the blood treatment, conveying in the method according to the invention takes place by means of the blood pump in a second conveying direction which is opposite to the first conveying direction. For executing the method according to the invention, a first section of the arterial line section is or will be connected with a second section of the venous line section of the extracorporeal blood circuit.
The functional device according to the invention, which in particular is embodied as a blood cassette, comprises a venous line section and a venous addition point communicating herewith. The venous addition point is prepared and/or provided to be connected with an arterial needle connection of the arterial line section of an extracorporeal blood circuit.
The set according to the invention comprises at least one functional device according to the invention and at least one extracorporeal blood circuit. The arterial needle connection or a different section of the arterial line section of the extracorporeal blood circuit is prepared to be connected with the venous addition point of the functional device.
The blood treatment apparatus according to the invention is provided and embodied and/or equipped for executing the method according to the invention.
The control device according to the invention is suitable and provided and/or arranged and/or configured for executing the method according to the invention.
A digital, particularly a non-volatile storage medium according to the invention, particularly in the form of a machine-readable data storage device, particularly in the form of a disk, CD, EPROM or DVD, with electrically readable control signals may interact with a programmable computer system such that the mechanical steps of a method according to the invention are prompted. According to the invention a computer program product can be understood as, for example, a computer program which is stored on a storage device, an embedded system as a comprehensive system with a computer program (e.g. an electronic device with a computer program), a network of computer-implemented computer programs (e.g. a client-server system, a cloud computing system, etc.), or a computer on which a computer product is loaded, executed, saved or developed. In doing so, all or some of the mechanically executed steps of the method according to the invention may be prompted.
A computer program product according to the invention comprises a program code—e.g., volatile, transitory or non-transitory and saved on a machine-readable medium—for prompting the mechanical steps of the method according to the invention when the computer program product runs on a computer.
The term “machine-readable medium” as used herein denotes in certain embodiments of the present invention a medium containing data or information which is interpretable by software and/or hardware. The medium may be a data medium, like a disk, a CD, DVD, a USB stick, a flashcard, an SD card or the like.
A computer program according to the invention comprises a program code for prompting the mechanical steps of a method according to the invention when the computer program runs on a computer. A computer program according to the present invention can be understood as, for example, a physical software product, which is ready for distribution and contains a computer program.
It also applies for the computer program product according to the invention and the computer program according to the invention that all or some of the mechanically executed steps of the method according to the invention are prompted.
Embodiments according to the invention may comprise some or all of the following features in arbitrary combination. Advantageous developments of the present invention are each also subject of the dependent claims.
In all of the following embodiments, the use of the expression “may be” or “may have” and so on, is to be understood synonymously with “preferably is” or “preferably has,” respectively, and so on, and is intended to illustrate exemplary embodiments according to the invention.
The extracorporeal blood circuit is in certain embodiments of the present invention a tube set. In any case, the extracorporeal blood circuit is provided for extracorporeally conducting blood of a patient, e.g., during hemodialysis, hemofiltration, hemodiafiltration or the like.
In some embodiments according to the invention, the extracorporeal blood circuit is at least in sections embodied as an integral and, where appropriate, permanent part of the functional device, in others it is not. A freely movable tube section of the extracorporeal blood circuit may therefore continue in one piece or integrally on or in the functional device, e.g., a blood cassette, and vice versa.
A functional device is in certain embodiments of the present invention a device which is used in a blood treatment. Examples of functional devices include internal and external functional devices, medical disposables, in particular blood cassettes such as a disposable blood cassette, or other blood-conducting devices.
Exemplary embodiments of a blood cassette are in particular disclosed in the application of the Applicant with the publication number DE 10 2009 018 664 A1 having the title Externe Funktionseinrichtung, Blutbehandlungsvorrichtung zum Aufnehmen einer erfindungsgemäβen externen Funktionseinrichtung, sowie Verfahren, which was submitted to the German Patent and Trademark Office on Apr. 23, 2009, and in the application of the Applicant with the publication number DE 10 2009 024 468 A1 of the same title, which was submitted to the German Patent and Trademark Office on Jun. 10, 2009. The respective disclosures are herewith fully incorporated by way of reference.
In certain embodiments according to the invention, the functional device as external functional device is not a part of the blood treatment apparatus, i.e., no integral element of it. In other embodiments, the functional device may be a part of the blood treatment apparatus.
A blood treatment apparatus is provided and/or embodied for performing or prompting a medical treatment, in particular a blood treatment of the patient, e.g., a dialysis. For this purpose, the blood treatment apparatus is connected with or comprises at least one extracorporeal blood circuit which comprises a line having interior portions.
The arterial line section of the extracorporeal blood circuit is in certain embodiments of the present invention the line section in which the patient blood that leaves the body of the patient for the purpose of the extracorporeal blood treatment flows and in which it is present before it enters the blood treatment device, e.g., a dialyzer.
In certain embodiments of the present invention, the first section of the arterial line section is or comprises the arterial needle connection to the patient, e.g., the arterial needle connection in a double-needle dialysis treatment.
The venous line section of the extracorporeal blood circuit is in some embodiments of the present invention the line section from which the extracorporeally treated patient blood flows towards or back into the body of the patient after its treatment in a blood treatment device, e.g., a dialyzer.
In certain embodiments of the present invention, the second section of the venous line section is or encompasses a venous port, for example a venous addition port or a venous addition point. It may, where appropriate, be used or provided for the addition of substituate liquid, calcium citrate, heparin or the like to the patient blood flowing in the venous line section of the extracorporeal blood circuit.
In certain embodiments of the present invention, the venous addition point of the venous line section of the extracorporeal blood circuit leads, optionally directly or indirectly, into the venous line section upstream from a blood chamber and upstream from a clot catcher.
In some embodiments according to the invention, the venous addition point is an integral part of a blood cassette.
The blood treatment apparatus comprises a blood pump for conveying blood within the line interior of the extracorporeal blood circuit.
In certain embodiments of the present invention, the first conveying direction, as is customary during blood treatment, corresponds to a conveying direction from the arterial access (blood withdrawal point) of the patient to a blood treatment device, for example a blood filter or a dialyzer, and subsequently through the venous line section of the extracorporeal blood circuit to the venous access (blood return point).
The second conveying direction which is opposite the first conveying direction therefore proceeds in such embodiments from venous to arterial.
“Removing blood” denotes in certain embodiments of the present invention completely—or basically or nearly completely—or partially removing blood from the extracorporeal blood circuit at the end of a blood treatment session.
Reinfusing the blood removed from the extracorporeal blood circuit into the vascular system of the patient itself is in some embodiments of the present invention not a part of the method according to the invention, in others, however, it is.
In certain embodiments of the present invention, the blood treatment apparatus comprises at least one second conveying device. The second conveying device serves to introduce at least a second fluid which is different from the blood, for example a substituate liquid, into the line interior portions of the extracorporeal blood circuit and/or to convey the fluid herein.
Introducing the second fluid, hereafter simplifyingly—but not restrictively—denoted as substituate liquid, into the line interior of the extracorporeal blood circuit by operating the second conveying device, hereafter simplifyingly—but not restrictively—denoted as substituate pump, in certain embodiments of the present invention takes place after connecting the first section of the arterial line sections with the second section of the venous line section.
In some embodiments according to the invention, the blood pump is operated in the second conveying direction such that the flow of the substituate liquid which is or was introduced into the line interior of the extracorporeal blood circuit is separated into at least a first and a second partial flow. The first partial flow of the substituate liquid moves towards a blood treatment device, the second partial flow of the substituate liquid moves in the second conveying direction.
In certain embodiments of the present invention, the method according to the invention encompasses disconnecting the first section.
In some embodiments of the present invention, the method according to the invention encompasses connecting the first section with a venous addition point of the venous line section of the extracorporeal blood circuit or with a venous addition point of the functional device (for example the blood cassette).
In certain embodiments of the present invention, the second conveying device and the blood pump are started, in particular basically or nearly or completely, at the same time.
The feed rates of the second conveying device and the blood pump in some embodiments of the present invention are or will be set such that a section of the venous line section, e.g., from a predilution point or from a predilution valve to the venous addition point or to a point at which fluid from the venous line section and fluid from the arterial line section are joined or meet, are not emptied of blood before a section of the arterial line section, e.g., until its connection with the venous addition point or up to the point at which fluid from the venous line section is joined with fluid from the arterial line section or both fluids meet.
In certain embodiments of the present invention, the feed rate of the blood pump is (initially, always, or on average) lower than the feed rate of the second conveying device or is adjusted accordingly.
In some embodiments of the present invention, the feed rates of the blood pump and/or of the second conveying device are monitored and/or regulated by means of pressure monitoring and/or pressure measurement and/or pressure limitation during the removal of the blood.
In doing so, in certain embodiments of the present invention, the feed rate q_V_Sub of the second conveying device is set according to the formula
                              q_V          ⁢          _Sub                =                  q_V          ⁢          _BP          ⁢                      (                          1              +                                                V_ven                  ⁢                  _min                                V_art                                      )                                              (        I        )            
In formula (I), V_ven_min denotes in certain embodiments of the present invention the volume of the venous line section including the intake volume of a smallest blood treatment device (for example, with reference to various blood treatment devices to be used at a blood treatment apparatus, see below); q_V_BP denotes the feed rate of the blood pump, V_art the volume the arterial line section or section may take in.
The “smallest blood treatment device” is in certain embodiments of the present invention the blood treatment device among a multitude of blood treatment devices, e.g., blood filters or dialyzers, which are prepared for use with the considered blood treatment apparatus (e.g., concerning the present connections, admissions or addition points and so on), which may take in the least volume or the least fluid.
A typical value for q_V_Sub may result in:q—V_Sub=50 ml/min(1+(60 ml/60 ml)=100 ml.
In certain embodiments of the present invention, the feed rate of the second conveying device is set such that at the venous addition point—or at a point at which fluid from the venous line section is joined with or meets fluid from the arterial line section—blood (from a line) and substituate liquid (from a different line) of the same degree of dilution meet.
In certain embodiments of the present invention, the method according to the invention encompasses setting the feed rate q_V_Sub of the second conveying device and the feed rate q_V_BP of the blood pump towards each other—individually for each used blood treatment device—according to the formula
                                          q_V            ⁢            _BP                                q_V            ⁢            _Sub                          =                              V_art            ⁢            _S            ⁢            _h                                              V_Dial              ·              F                        +                          V_art              ⁢              _S              ⁢              _h                                                          (        II        )            
In formula (II), V_art_S_h indicates the substituate volume which has to be conveyed into the arterial line section so that at the end of the arterial line section a hematocrite (HKT) value of ˜0.02 occurs; V_Dial indicates the volume of the blood treatment device, and F indicates a dimensionless correction factor which indicates the ratio of the actual amount of liquid required for rinsing the blood treatment device (until a hematocrite HKT of about 0.02 is reached) to its nominal filling volume on the patient side.
V_art_S_h may have been or may be experimentally determined once for an averaged patient hematocrite. The same applies for the dimensionless factor F.
A typical value for q_V_BP/q_V_Sub may result in:q—V_BP/q_V_Sub=60 ml/(80 ml*1.5+60 ml)=⅓.
In certain embodiments of the method according to the invention, the intention is to stop the blood pump or reduce its feed speed or feed rate, before substituate liquid downstream (with regard to the second conveying direction or to the method according to the invention) from the venous addition point or the point at which fluid from the venous line section and fluid from the arterial line section are joined or meet.
This may in certain embodiments of the present invention advantageously contribute to a stronger and/or improved flushing of the blood treatment device.
The time for stopping the blood pump or for reducing its feed rate is in certain embodiments of the present invention determined with the aid of the arterial air bubble detector/optical detector (also known as ABD/OD) which is integrated in the extracorporeal blood circuit. This may advantageously increase the accuracy of determination of the time for stopping.
In other embodiments of the present invention, the method according to the invention encompasses stopping the second conveying device or reducing the speed or the feed rate of the second conveying device before substituate liquid gets downstream (with regard to the second conveying direction or to the method according to the invention) from the venous addition point or the point at which fluid from the venous line section and fluid from the arterial line section are joined or meet. This may advantageously contribute to a stronger and/or improved flushing of the arterial line section of the extracorporeal blood circuit. The blood pump is further operated in such embodiments, or it is not further operated.
In certain embodiments of the present invention, the method according to the invention encompasses checking the connection of the first section, e.g., of the arterial needle connection, of the extracorporeal blood circuit at the venous addition point of the venous line section of the extracorporeal blood circuit (connection test).
In certain embodiments of the present invention, checking encompasses creating a pressure balance.
In such embodiments the intention may be to stop the blood pump and/or the second conveying device. Further, the intention may be to open or keep the arterial clamp open.
In certain further embodiments of the present invention, checking encompasses determining a diastolic patient pressure. A minimum value of the diastolic patient pressure may be saved over a time period of, e.g., 2.5 s. Subsequently, a negative pressure is created by means of the blood pump which conveys in the first conveying direction, i.e. forwards, wherein the venous clamp is opened or is already open. In certain embodiments of the present invention, it is defined that the vascular pressure of the patient has to drop by 50 mmHg within a time period of 2.1 s in order for the connection test to be considered to be passed. Alternatively, other values for pressure drop and/or times than the ones named here may be considered. If the desired and/or required pressure reduction has taken place not at all or not within the predetermined time, the connection test may be considered to be failed.
The functional device according to the invention is in some embodiments according to the invention embodied as disposable.
In certain embodiments according to the invention, the venous addition point of the functional device is embodied to create a fluid connection by simply clamping, attaching or screwing together an arterial needle connection or another section of the arterial line section of the extracorporeal blood circuit.
In some embodiments according to the invention, the venous addition point of the functional device and the arterial needle connection or another section of the arterial line section of the extracorporeal blood circuit are from the same connector system, e.g., Luer connectors, or female and male connector.
In certain embodiments according to the invention, the connection geometry of the venous addition point is embodied the same as or corresponds to the connection geometry of an arterial needle by means of which the extracorporeal blood circuit is connected for its use.
The control device according to the invention is in some embodiments according to the invention embodied as a regulating device.
The blood treatment device according to the invention is in some embodiments according to the invention embodied as a hemodialysis apparatus or hemofiltration apparatus or hemodiafiltration apparatus.
The blood treatment device according to the invention comprises in certain embodiments according to the invention at least one control device according to the invention.
Some or all embodiments according to the invention may comprise one, more or all of the advantages named above and/or hereafter.
The present invention provides a simple and not very elaborate method for removing blood from an extracorporeal blood circuit after a blood treatment session as well as corresponding apparatuses. By removing blood at the end of the treatment, the risk of contamination may advantageously be reduced during further use or disposing of the blood circuit.
In certain embodiments according to the invention, the method allows for completely returning blood present in the extracorporeal blood circuit at the end of the blood treatment session to the vascular system of the patient via a venous connection with the vascular system of the patient. Infusing substituate liquid or another fluid to the patient at the same time is hereby preventable.
The method according to the invention may advantageously be implemented in treatment apparatuses already known from practice just by means of a simple to perform software update. The blood treatment apparatuses known from practice often already comprise the required machine elements.